Magnetic fields and gas in the cluster-influenced spiral galaxy NGC 4254 I. Radio and X-rays observations
Magnetic fields and gas in the cluster-influenced spiral galaxy NGC 4254 I. Radio and X-rays observations
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受星团影响的螺旋星系 NGC 4254 中的磁场和气体 I. 射电和 X 射线观测
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发表时间：
2007
期刊：
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通讯作者：
R. Beck
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文献类型：
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作者：
K. Chyży;M. Ehle;R. Beck
目标。射电观测可以显示星系团如何受到各种环境因素的影响，这些因素扰动了它们的形态，并改变了星际介质（ISM）的性质，特别是其磁场的特征。方法.我们在三个频率（8.46，4.86和1.43 GHz）对NGC 4254进行了高分辨率和高灵敏度的射电偏振VLA观测。干涉测量的数据进行了扩展与单盘（100米Effelsberg）的意见。接下来，我们在X射线和紫外光下进行了灵敏的XMM-牛顿观测，以研究热气体成分及其与热星系团介质的可能相互作用。对于各种气相之间相互作用的完整图片，我们还使用了光学，H i和红外（斯皮策）数据。结果在8.46 GHz和4.86 GHz的总射电强度的分布揭示了一个全球性的不对称性，更分散和几乎两倍大的扩展到北部比南部。射电偏振强度更不对称，在南盘边缘有一个奇怪的亮脊，位移到局部密度波的下游。磁臂也可以在其他磁盘部分看到，大多数（但不总是）避免附近的光学螺旋臂。从整个星系盘的热X射线气体的空间分辨发射，其软成分密切跟踪恒星形成区，被检测到。热成因的各种气体成分表现出很强的小波互相关（rw ≥ 0.8），但偏振强度与热辐射和X射线辐射相关（rw =-0.4）。局域射电非热红外关系的斜率<1，比射电热红外关系的斜率（≥1）小。利用基于射电热辐射的恒星形成率（SFR），我们发现在Hα发光的恒星形成中，消光系数更高
Aims. Radio observations can show how cluster galaxies are affected by various environmental factors, that perturb their morphology, as well as modify properties of the interstellar medium (ISM), especially the characteristics of its magnetic field. Methods. We made high-resolution and high-sensitivity radio-polarimetric VLA observations of NGC 4254 at three frequencies (8.46, 4.86, and 1.43 GHz). The interferometric data were extended with single-dish (100-m Effelsberg) observations. Next we performed sensitive XMM-Newton observations in X-rays and UV light to investigate the hot gas component and its possible interaction with the hot cluster medium. For a complete picture of the interplay between various gas phases, we also used optical, H i, and infrared (Spitzer) data. Results. The distribution of total radio intensity at 8.46 GHz and 4.86 GHz reveals a global asymmetry with a more diffuse and almost two times larger extension to the north than to the south. The radio-polarized intensity is even more asymmetric, showing a strange bright ridge in the southern disk edge, displaced to the downstream side of the local density wave. Magnetic arms can also be seen in other disk portions, mostly (but not always) avoiding nearby optical spiral arms. Spatially-resolved emission of hot X-ray gas from the whole galactic disk, with its soft component closely tracing star-forming regions, is detected. Various gas components of a thermal origin show strong wavelet crosscorrelations (rw ≥ 0.8), but the polarized intensity anticorrelates (rw = −0.4) with the thermal and X-ray emission. The slope of the local radio nonthermal-infrared relation is <1, thus smaller than for the radio thermal-infrared one (≥1). Using the radio thermal emission-based star-formation rate (SFR), we find higher extinction in more Hα luminous star-forming